Favouritism for the Conservative Leadership race has been switching back and forth between Boris Johnson and Theresa May all day. At one stage May went down to 2.34 (43%) but tonight Johnson is back in front at 2.3 (43%) to her odds of 3.1 (32%). I think this is right, and managed to jump aboard the bandwagon at 2.5 (40%), as advised on Twitter.

New bet on Next Tory Leader: 80 units Boris Johnson @ 2.5. Endorsements from Remainers make him sure to reach the final 2.

Here’s why. First and foremost, it appears certain that he’ll reach the final, head-to-head run-off, where Tory members will ultimately decide. It is by no means certain that he’ll win that finale but in that scenario it’s very hard to imagine him being any bigger than 2.5. He could, of course, be regarded a certainty and be something like 1.2.

Second, he will certainly be the most prominent Brexit supporter, and possibly the only one in the race. Andrea Leadsom is reportedly undecided and she could potentially throw a spanner in the works of this theory, but I wouldn’t mind a punt that she backs Boris, perhaps with a view to becoming his Chancellor. Liam Fox has also been mentioned but would be a big outsider.

138 of their 330 MPs backed Leave and their block vote is enough alone to guarantee a place in the last two. However several Remain supporters have come out and endorsed Johnson today – Nicholas Soames, Liz Truss and Nicholas Boles.

If as discussed earlier, George Osborne makes a deal in exchange for a top job, he could bring plenty more with him. With each one, Johnson’s claim to be the unity candidate his party craves is enhanced. I wouldn’t overestimate hostility from Remain supporters among the ranks of Tory MPs – many or even most were regarded as Eurosceptic when elected, just like David Cameron.

This is the general nature of leadership races. The presumed front-runner bags dozens of endorsements from ambitious types, keen to go onside with the winning team early. The market responds accordingly. If as I expect, Boris wins the first round of voting, he should go heavily odds-on.

None of this is to say Boris doesn’t have weaknesses, nor that there is an ‘Anyone but Boris’ vote. I just wonder how large it is and, now the promising Stephen Crabb is in the race, May is unlikely to dominate that vote in the first round. Plus his weakness – lack of detail and seriousness – is to some extent negated by the close support of Michael Gove.

With much of his party on the verge of open revolt as Britain’s referendum on EU membership nears, David Cameron felt the need this weekend to stress that if the country votes to leave against what are now obviously his wishes, rather than resign, he would try and make it work.

We don’t know the exact date of the referendum yet but many suspect it will be this summer. Whether 2016 or 2017, the issue will dominate UK politics in the months ahead, and has profound implications for the race to succeed Cameron as Conservative Party Leader. Given that he’s already said he won’t run again in 2020, this is effectively a contest to be Next Prime Minister.

When I last wrote about this in March, tipping George Osborne at [9.4], it was far from certain that either man would still be in government now. As it turned out, a famous, against-the-odds election win worked wonders for this supreme strategist and he’s been red-hot on the Betfair market ever since.

The chancellor is now [2.94] favourite to succeed his long-term friend and ally, with punters assuming his strategic brain and stewardship of the economy mean he’s the darling of MPs and the Tory members who will ultimately decide. My advice, however, is to bank the profit and switch horses. Fast!